Stifel formula

The Stifel's formula is:

$(\begin{matrix} m \\ n \end{matrix}) + (\begin{matrix} m \\ n + 1 \end{matrix}) = (\begin{matrix} m + 1 \\ n + 1 \end{matrix})$

Example

Let's see how it is applied:

$(\begin{matrix} 5 \\ 2 \end{matrix}) + (\begin{matrix} 5 \\ 3 \end{matrix}) = (\begin{matrix} 6 \\ 3 \end{matrix})$

$(\begin{matrix} 2 \\ 1 \end{matrix}) + (\begin{matrix} 2 \\ 2 \end{matrix}) = (\begin{matrix} 3 \\ 2 \end{matrix})$

$(\begin{matrix} 90 \\ 89 \end{matrix}) + (\begin{matrix} 90 \\ 88 \end{matrix}) = (\begin{matrix} 91 \\ 89 \end{matrix})$